Funny you mention Alakazam, Machamp, Golem and Gengar as they're the exact 4 TRADE ONLY EVOS in Gen 1; weird coincedence.
The Pokemon who more or less appeared in EVERY version of the game, and aren't ranked yet, ignoring oddities like Pokemon XD are moer or less the following:
Golem (used by a lot of people since RBY; staple early game tank whose got good offense, and you'll hate fighting them early on before you get actual special attacks and/or grass/water/fighting moves. Furthermore, 3 out of 4 of the FIRST GYM LEADERS use a Geodude.)
Alakazam (your token Psychic Type in every gen; almost everyone has, at one point, used a Kadabra. He's fundamentally the same in all games too, much like Golem; some changes in averages, loss of special defense, but that's about it; he's always relying on the same tricks and such.)
Magikarp/Gyarados (The token "Raise from crap, get something supposedly awesome!" Pokemon. How good he is varies from Generation to Generation. I place them like this, instead of listing the evo, cause I might actually support Magikarp over Gyarados cause he has far less interp issues between Generations (HE'S ALWAYS PUNY!), and probably more well known/iconic/etc.)
Psyduck/Golduck (listed separately for same reason as Magikarp/Gyarados. Anyway, here's a Pokemon almost no one uses, and really only exists for HM Slaving...flipside, ITS FREAKING PSYDUCK.)
Crobat (you fight way too many Zubats throughout the game, you know exactly what they're capable of, and you even fight plenty of Golbats too; I think he's a good choice if only cause of the mere amounts of these guys you face.)
Tentacruel (Zubats of the sea! Only less memorable since their annoyance factor isn't nearly as a high...)
Machamp (well known physical slugger, though he gets like 5x better between Gen 1 and later Gens.)
I think that more or less covers Pokemon who are in every single version of every single generation. I think Pokemon like Gengar come close but miss out on something like Gen 3 (I know that despite their being a Ghost E4 Member, you did not face a Haunter/Gengar there, which makes me think there is no Gastly series in Hoehn), though are probably well known enough to just say "whatever, he can get in."
Just for curiousity sake, here's Pokemon typings we have represented in the DL:
Normal: Nothing! (AN EXCUSE TO RANK STARAPTOR?!?!?)
Fire: Charizard, Moltres, Typhlosion, Ho-oh, Blaziken
Grass: Venusaur, Meganium, Sceptile
Water: Blastoise, Feraligatr, Suicune, Swampert, Kyogre
Electric: Pikachu, Zapdos
Ground: Swampert, Groudon
Psychic: Mewtwo, Lugia
Fighting: Blaziken
Flying: Charizard, Articuno, Zapdos, Moltres, Lugia, Ho-oh, Rayquaza
Dragon: Rayquaza
Ghost: NOTHING! (Excuse to rank GENGAR?!?!)
Poison: Venusaur
Bug: NOTHING! (Excuse to rank HERACROSS AND BUTTERFREE!!!?)
Steel: NOTHING! (And this is why we need to rank MECHAPENGUIN. Also Piplup hype)
Dark: NOTHING! (DARKR-*SHOT*)
Rock: NOTHING! (*insert Golem hype here*)
Ice: Articuno
NOTE: My hypes are just me being silly, feel free to ignore them <_<
